When modularity, affordability, and quality are all important the Mk4 T is the
upper of choice. The Mk4 T introduces CMMG's RKM series of KeyMod free float
hand guards, nitrided 4140 CrMo steel barrel in a medium taper profile, and
GMMG's lifetime quality guarantee.

Caliber: 9mm

Barrel: 16" Barrel, Nitrided 4140 Chrome-Moly
Steel

Muzzle: A2 comp., threaded 1/2-36

Hand Guard: CMMG RKM11 KeyMod hand guard

Twist Rate: 1:10"

Receiver: Forged 7075-T6 AL M4 type

CMMG’s WASP FINISH

(Weapon Armament Surface
Protection)

Is a Salt Bath Nitride
Finish surface conversion process or more commonly referred to as
Nitriding. The Nitriding conversion is applied to the barrel inside and out,
along with the front sight base on our LE rifles and uppers. Nitriding offers
improved wear, abrasion, and corrosion resistance when compared to hard chrome
lining or phosphating. Unlike chrome lining, where the chrome is built up on
the surface, Nitriding converts the surface without the risk of dimensional
build up. CMMG has been utilizing this nitriding process for many years with
our LE series rifles.

searched everywhere for this upper and found it here significantly cheaper than anywhere else. My only complaint is that the takedown pin was a rather difficult to insert, as in it was way too tight. This isn't a $1500 upper though and it's works as expected so no problem.

Customer service was absolutely amazing though. Definitely felt like they made sure that I got exactly what I wanted. I'll definitely order from Right to Bear again.